1 | // Three-state boolean logic library |
---|
2 | |
---|
3 | // Copyright Douglas Gregor 2002-2004. Use, modification and |
---|
4 | // distribution is subject to the Boost Software License, Version |
---|
5 | // 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
---|
6 | // http://www.boost.org/LICENSE_1_0.txt) |
---|
7 | |
---|
8 | // Modifications by Orxonox to shape the third state into 'dontcare' instead |
---|
9 | // of 'indeterminate'. The difference is that 'dontcare' is actually a value |
---|
10 | // so that (dontcare == dontcare). |
---|
11 | // Also removed all logic operators except for == and != |
---|
12 | |
---|
13 | |
---|
14 | // For more information, see http://www.boost.org |
---|
15 | #ifndef ORXONOX_TRIBOOL_H |
---|
16 | #define ORXONOX_TRIBOOL_H |
---|
17 | |
---|
18 | namespace orxonox { |
---|
19 | |
---|
20 | /** |
---|
21 | * INTERNAL ONLY |
---|
22 | * The type of the 'dontcare' keyword. |
---|
23 | */ |
---|
24 | struct dontcare_keyword_t { }; |
---|
25 | |
---|
26 | /** |
---|
27 | * \brief Keyword for the dontcare tribool value |
---|
28 | */ |
---|
29 | const dontcare_keyword_t dontcare = dontcare_keyword_t(); |
---|
30 | |
---|
31 | /** |
---|
32 | * \brief A 3-state boolean type. |
---|
33 | * |
---|
34 | * 3-state boolean values are either true, false, or |
---|
35 | * dontcare. |
---|
36 | */ |
---|
37 | class tribool |
---|
38 | { |
---|
39 | public: |
---|
40 | /** |
---|
41 | * Construct a new 3-state boolean value with the value 'false'. |
---|
42 | * |
---|
43 | * \throws nothrow |
---|
44 | */ |
---|
45 | tribool() : value(false_value) {} |
---|
46 | |
---|
47 | /** |
---|
48 | * Construct a new 3-state boolean value with the given boolean |
---|
49 | * value, which may be \c true or \c false. |
---|
50 | * |
---|
51 | * \throws nothrow |
---|
52 | */ |
---|
53 | tribool(bool value) : value(value? true_value : false_value) {} |
---|
54 | |
---|
55 | /** |
---|
56 | * Construct a new 3-state boolean value with an dontcare value. |
---|
57 | * |
---|
58 | * \throws nothrow |
---|
59 | */ |
---|
60 | tribool(dontcare_keyword_t) : value(dontcare_value) {} |
---|
61 | |
---|
62 | /** |
---|
63 | * \brief Compare tribools for equality |
---|
64 | * |
---|
65 | * \returns the result of comparing two tribool values. |
---|
66 | * \throws nothrow |
---|
67 | */ |
---|
68 | inline bool operator==(tribool y) |
---|
69 | { |
---|
70 | return (this->value == y.value); |
---|
71 | } |
---|
72 | |
---|
73 | /** |
---|
74 | * \overload |
---|
75 | */ |
---|
76 | inline bool operator==(bool y) { return (*this) == tribool(y); } |
---|
77 | |
---|
78 | /** |
---|
79 | * \overload |
---|
80 | */ |
---|
81 | inline bool operator==(dontcare_keyword_t) |
---|
82 | { return tribool(dontcare) == (*this); } |
---|
83 | |
---|
84 | /** |
---|
85 | * \brief Compare tribools for inequality |
---|
86 | * |
---|
87 | * \returns the result of comparing two tribool values for inequality. |
---|
88 | * \throws nothrow |
---|
89 | */ |
---|
90 | inline bool operator!=(tribool y) |
---|
91 | { |
---|
92 | return !((*this) == y); |
---|
93 | } |
---|
94 | |
---|
95 | /** |
---|
96 | * \overload |
---|
97 | */ |
---|
98 | inline bool operator!=(bool y) { return (*this) != tribool(y); } |
---|
99 | |
---|
100 | /** |
---|
101 | * \overload |
---|
102 | */ |
---|
103 | inline bool operator!=(dontcare_keyword_t) |
---|
104 | { return (*this) != tribool(dontcare); } |
---|
105 | |
---|
106 | /** |
---|
107 | * The actual stored value in this 3-state boolean, which may be false, true, |
---|
108 | * or dontcare. |
---|
109 | */ |
---|
110 | enum value_t { false_value, true_value, dontcare_value } value; |
---|
111 | }; |
---|
112 | |
---|
113 | /** |
---|
114 | * \overload |
---|
115 | */ |
---|
116 | inline bool operator==(bool x, tribool y) { return tribool(x) == y; } |
---|
117 | |
---|
118 | /** |
---|
119 | * \overload |
---|
120 | */ |
---|
121 | inline bool operator==(dontcare_keyword_t, tribool x) |
---|
122 | { return tribool(dontcare) == x; } |
---|
123 | |
---|
124 | /** |
---|
125 | * \overload |
---|
126 | */ |
---|
127 | inline bool operator!=(bool x, tribool y) { return tribool(x) != y; } |
---|
128 | |
---|
129 | /** |
---|
130 | * \overload |
---|
131 | */ |
---|
132 | inline bool operator!=(dontcare_keyword_t, tribool x) |
---|
133 | { return tribool(dontcare) != x; } |
---|
134 | |
---|
135 | } // end namespace orxonox |
---|
136 | |
---|
137 | #endif // ORXONOX_TRIBOOL_H |
---|
138 | |
---|